In the system of the invention a strong applied electric field is crossed with (i.e., established essentially at right angles to) a very strong annular-confinement magnetic field directed axially within an annular confinement chamber, and a stream or several streams of high-kinetic-energy tightly-looping fusible ions mixed with space-charge-neutralizing electrons is by ion and electron optical methods introduced into the chamber at a location within but non-adjacent to the walls of the annular chamber, the stream having appropriate values of electric potential and potential gradient and cross-sectional dimensions, these being controlled by circumstances of the introduction of the stream into the chamber, whereby the ions and space-charge-neutralizing electrons will move generally arcuately at right angles to both field directions at a crossed-field advance velocity determined by the electric field and the magnetic flux density thus being approximately at right angles to the annular axis of the chamber. The ions of the stream, because of the strength of the magnetic field, assume a confined tightly-looping quasi-trochoidal type of motion, or motion segments, with the kinetic energy in the small diameter looping components of the ion motions greatly exceeding the kinetic energy in the relatively slow crossed-field advance motion. The duration of the confinement into controlled flow paths is made sufficient to produce fusion events at a substantial rate resulting in the release of high kinetic energy neutrons and positively-charged particles whereby this kinetic energy may be converted into usable heat, chemical energy or directly converted into electric energy. The method and apparatus of the invention utilize crossed strong electric and magnetic fields to control the location, dimensions, and flow of the stream, and by the use of interrelated potentials impressed upon the stream as related to potentials within the location in the fusion chamber at which the stream is introduced maintains the stream out of contact with the chamber walls. Because the ion energies and densities are controlled by the circumstances of their introduction into the fusion chamber, they can in combination be large enough so that throughout the duration of the ions' flight paths within the fusion chamber, a duration that is controllable, the fusion power generation per unit volume of stream can be great enough so that substantial power generation can be obtained in a relatively small volume of the reacting stream.
The invention pertains to a system for producing nuclear fusion, and particularly relates to the confinement, that is, to the control of the location, dimensions, potential structure, and flow rate, of a stream of fusible positive ions, with associated separately produced electrons that are present solely to neutralize the ion space charge, such control being by the use of crossed electric and magnetic fields having directions wholly or primarily at right angles to one another.
The high kinetic energy ions introduced into the annular reaction chamber assume a looping quasi-trochoidal type of motion. This motion is characterized in the invention by the kinetic energies in the small diameter looping components of the ion motions exceeding, by a factor of the order of 10 or more, and extending in cases to factors of thousands or tens of thousands or more, the kinetic energies in the relatively slow crossed-field-advance motions with which the ions circulate circumferentially around the axis of the annular reaction chamber.
While the advantages of producing energy, in the form of heat or electricity, through the nuclear fusion process has long been appreciated, because of the very high kinetic energies (often expressed in terms of extremely high temperatures) at which fusion occurs, and because of other physical limitations, it has not been possible to bring about adequate confinement or control and so utilize nuclear fusion principles in a commercial manner.
It has been recognized that nuclear fusion reactions can be confined within magnetic fields, and fusible fuel which has been completely ionized to form an assembly of positive ions and free electrons, often called a plasma, has been proposed to be confined within crossed electric and magnetic fields as disclosed in U.S. Pat. No. 3,029,199. In that patent the magnetic flux lines loop around the interior axis of the annular chamber, the ion and electron stream therefore circulating generally parallel to that interior axis, occupying only a very limited portion of the available magnetic field region. Furthermore, in U.S. Pat. No. 3,029,199 the ionization and imparting of kinetic energy to the ions is the result of passage of electric current between the electrodes of the chamber, thus establishing a plasma, a method that has not been used successfully to produce the ion kinetic energy needed for fusion.
In U.S. Pat. No. 3,120,475 there is disclosed an electric mirror machine that employs electrodes at differing potentials in combination with a magnetic field. Its primary high density, high energy confined flow occurs parallel to the axis of the magnetic field and for the most part parallel to a congruent electric field, the magnetic and electric fields being almost entirely congruent in the important region where the charged particles are reflected from their approach to the two ends of the enclosure. In this patent the primary purpose of the electric field is to cause reflections of the ions back and forth from and between the two on-axis ends of the enclosure in their movements essentially parallel to the magnetic flux lines and two positive repelling electrodes are required on the convergent end sections; to cause the repelling field to exist there must be a strongly negative electrode elsewhere, this being the electrode centered on the meridian plane extending parallel to the axis along the inner surface of the central portion of the enclosure, which must be remote from the active playing region where the plasma exists in order not to interfere with it either physically or by electric field influences. Thus two electrodes, both positive, are at the extreme ends and near the axis of the structure, whereas the negative electrode centers in the central plane of the structure and is remote from the axis. U.S. Pat. No. 3,120,475 employs ion injection from a simple ion gun, a method that is not feasible with magnetic flux densities strong enough to provide confinement at ion densities and energies needed for fusion.
In my U.S. Pat. No. 3,501,376 I disclose a method and apparatus for confining a monopolar (i.e., using ions alone) stream of fusible ions by using crossed electric and magnetic fields. However, the prior art disclosures have not been sufficient to overcome the many problems in creating and maintaining a commercially usable fusion reaction, and one of the problems results from the inability of known apparatus to maintain the confinement of fusible positive ions at a sufficient combination of high kinetic energy and high density to permit a sufficient rate of neutron and positively-charged particle production.
In the majority of existing proposed engineering applications for fully ionized gases, whether for fusion or other purposes, the presence of a magnetic field, usually an extremely strong magnetic field, is an essential item. In many of the related analytical treatments and engineering studies great emphasis is placed on the powerful magnetic influences that prevent the "guiding centers" of the charged particles' motions from moving across magnetic flux lines from one "tube of flux" to another. The guiding center concept arises from the fact that in a strong magnetic field a charged particle's motion consists of a small diameter circular looping in the plane at right angles to the magnetic field direction, superimposed on certain kinds of straight line or slowly curving motions. It is helpful to consider the straight line or slowly curving motions as being translations of the guiding centers of the loop, no physical object being at a "guiding center," with the looping motion as a whole translating as movements of the guiding center require, the looping component remaining parallel to its original plane. In the absence of any electric field, the guiding center can move only in one direction, i.e., that of the magnetic field, to or fro. This is a very strong limitation, particularly for the nuclear fusion reaction art wherein the magnetic field may often be strong enough so that even for very large kinetic energies of the ions the diameter of their looping motions is only a very few centimeters, or even a very few millimeters, and therefore in many cases small relative to the dimensions of the fusion-reaction chamber. This powerful tendency for confinement of the guiding center to its original position in the magnetic-flux structure is described in terms of "magnetic pressure", which is proportional to the square of the magnetic flux density. Closely related to this behavior is the fact that the magnetic force on a charged particle does not add to nor subtract from its kinetic energy, because the magnetic force is always at right angles to the direction of the particle's motion, so does not affect its scalar velocity, nor its kinetic energy. In a converging magnetic field translation of the guiding center in the direction of the magnetic field will alter the division of the kinetic energy as between the looping motion energy content and the translational motion energy content. This happens in the familiar magnetic mirror machine intended to produce fusion, being a behavior wholly different in principle from that occurring in the electric mirror apparatus of U.S. Pat. No. 3,120,475 referred to earlier.
However, in the presence of an electric field that has its major component at right angles to the direction of the magnetic field, there is a very powerful influence that compels the guiding centers to move across magnetic flux lines, in a direction at right angles to both the electric and the magnetic fields, thus producing the straight line or slowly curving component of motion referred to earlier. Under these conditions the resulting movement has as one component what is called the "crossed-field advance velocity" in the prescribed direction. Electromagnetic theory, and also simple rule-of-thumb considerations, require that for the straight line crossed-field advance velocity existing when both fields are uniform, this velocity expressed in meters per second must equal the cross direction electric field component in volts per meter divided by the magnetic flux density in webers per square meter. This crossed-field advance velocity is the same in direction and magnitude for particles of the two kinds of electric charge, and is independent of the mass of the particle and the amount of its electric charge, and is therefore the same for the electrons as for the positive ions. The direction of the looping component superimposed on the crossed-field advance velocity is clockwise for one kind of particle, and is counterclockwise for the other. The radius of the looping component is inversely proportional to the magnetic flux density, proportional to the square root of the kinetic energy content of the looping component of the motion, and proportional to the square root of the mass of the particle. Because of the dependence on particle mass, the radius of the electron looping is for given kinetic energy very much smaller than for the ions, for example by a factor of about 60 for deuterons; in addition, for the embodiments envisioned for this invention the electron energies are expected to be substantially less than the ion energies.
For any charged particle so moving, the total average kinetic energy is the simple sum of three energies; that in the crossed-field advance motion, that in the circular looping motion superimposed on the advance motion, and that in the linear motion parallel to the direction of the magnetic field. For each particle the angular velocity in radians per second is invariant, being numerically the same as the cyclotron radian frequency governed by the magnetic flux density and the ratio of electric charge to mass for the particle. Even in the presence of extensive occurrence of collisions between particles, every individual segment of a particle's motion will have the crossed-field advance velocity as a component of its motion in the prescribed direction; thus a swarm of particles having many collisions will move as a body with the crossed-field-advance direction and magnitude. When tightly-looping high-kinetic-energy particle motions appear in the presence of curvature and convergence of the crossed fields, but with the loops being small enough so that there occur only very minor changes in field directions or intensities within individual loops, the crossed-field advance concept applies for the motions of the guiding centers, with however, a centrifugal force effect contributing to the governing of the magnitude of the crossed-field advance velocity; however, this velocity's direction remains always at right angles to both fields. In the embodiments of my invention these centrifugal force effects will contribute only to a very small degree to the governing of the magnitude of the crossed-field advance velocity of the guiding centers.
This requirement for the existence of the crossed-field advance velocity of the guiding centers is potentially a very powerful resource for compelling streams of charged particles, of ions or electrons or both intermixed, to move across magnetic flux lines in prescribed paths, and this can include movement from outside to inside of a region of very strong magnetic field, as for example into a region in which the very strong magnetic field confines a fully ionized gas at energies adequate to cause fusion. It is also a resource that can be used to compel streams of such particles to circulate in crossed-field advance paths, and at controlled rates of advance, within a crossed-field fusion reaction chamber, but this resource has not been utilized to its potential in the prior art devices.